I contacted customer support at Arches and the representative told me that it's acceptable to paint on both sides of watercolor paper. So, it's safe to say that there's no “wrong” side to paint on, it's more of a personal preference.
Unless it's a watercolor board or canvas that has only one surface prepped for watercolor (the "backside" is usually reserved for mounting), the only rule is... Use whichever side of watercolor paper that you prefer.
It really is a question of personal preference. I've found very little difference on both faces of Arches, Winsor & Newton, and Sunders Waterford papers. I often use both sides for sketching. You get double the value out of each sheet!
The Correct Side of Watercolor Paper
Well, after some research I found that when purchasing sheets of watercolor paper the manufacturer will stamp their logo usually onto the corner of the sheet to signify that this is the “front” side you are supposed to paint on.
Select either side of hot pressed paper to paint on because often there is little difference to the texture between the surfaces. You can always do a test paint of both sides to see which side you have a preference to paint on.
It is generally accepted that the correct side of the watercolour paper to paint on is the side from which the watermark is legible. For example, if you are using Saunders Waterford paper, the correct side would be the side on which the 'Saunders Waterford' Watermark is displayed the right way round.
It appears that Arches cold press cotton watercolor paper has been having an increased rate of sizing failure in 2020-2021. It is possible that during the pandemic supply shortages something changed with their core ingredients to make this paper more susceptible to this issue.
Arches Watercolor Paper is mould-made. Original Arches Natural White Watercolor Paper has been prized by artists since the founding ofﾠArches in 1492. This legendary paper is still made with natural cotton fibers, carefully selected for their absorbency and durability.
Watercolor paper for beginners:
I recommend beginning with 140# cold-pressed watercolor paper in either a natural or bright white. 140# paper is very common so it's easy to find and fairly affordable—much more so than heavy-weight paper—but will still hold up well under heavy washes.
Most people use the smoother side of the chart paper. On the other side which is slightly rough the colour or ink pens tend to smudge. Avoid using to watery paints.
“Arsh” is the closest.
Why Do I Need To Stretch Watercolour Paper? You need to Stretch Watercolour Paper if you are using a 140lbs / 300gsm Watercolour Paper or lighter or if you are applying a heavy watercolour wash to your paper. By Stretching your Watercolour Paper first, it prevents the paper from buckling.
Sketchbook Rule 8: Use only one side of the page OR use both sides of the page. This is another case of personal preference. I like the look of a very full sketchbook with something going on in every single page. Others prefer a cleaner look with sketches neatly positioned on one side of the paper.
From the first time I picked up a watercolor brush in 1972, Arches watercolor paper has been my preference for painting. I've "tested" different papers over the years, but none can match Arches brand - in my opinion - for consistent quality.
Rough, as suggested by the name, is the most textured watercolour paper. The deep pits in the paper are brilliant if you want to get the most out of the granulation of your watercolour paints. This heavily textured paper is well suited to those with a loose watercolour painting style.
Arches paper is a brand of air-dried paper that is used by printers and watercolorists. It has a warm white colour and is produced in hot-pressed, cold-pressed, and rough varieties. Arches paper is made in the village of Arches in the Vosges, France.
1. Arches Watercolor Block, 300 lb – Best Watercolor Paper Overall. Being one of the most well-known art supply manufacturers in the world, Arches produces a wide range of watercolor paper types. High-quality and efficient, its 300-pound block is one of the most popular and successful.
Arches Watercolor Paper is acid free, ph neutral, and made from 100% cotton fibers. These Archival Art Panels are available in three distinct textures. The Arches papers are archivally mounted and are reversible for future conservation of the art.
Arches Watercolor Paper is made the traditional way, on a cylinder mold, in France. The 100% cotton fibers are evenly distributed, making for a more stable paper that can withstand more water without warping or bleeding. Arches paper is sized with natural gelatin that prevents tearing or linting.
If properly stored watercolor paper will not expire. Keep proper humidity and store it flat. I have Arches thirty years old and in excellent condition.
But most fine artists prefer to use a minimum of 140 lb (300 gsm) paper. The lighter the paper, the more stretching it will require, and with paper less than 140 lbs, we recommend that you stretch it before use. To avoid having to stretch your paper, opt for a heavier weight.